I use this for curls with a barbell its unlike anything else cause the resistance gets harder as you complete the curl.I also use it for aiding in pullups put my knee through it when I cant do any more and it makes you lighter so you can do more reps. There are many more exercises you can do but once you do curls with it youll never stop. I attach 1 end to the bar & the other under my feet & spread them out. When you cant do anymore let go with you feet. Now you can do more until burnout. This is 40 inchs long.